Components of a wind turbine are controlled in their temperature to avoid the accumulation of moisture or humidity in the components.
Auxiliary power might be used to heat up respective components. Auxiliary power might be supplied by a Diesel-generator or by an electrical power grid, being connected with the wind turbine.
In specific situations the heating of the respective components might fail, e.g. the auxiliary power supply by the Diesel-generator might get lost due to a malfunction or the power supply by the electrical power grid might get lost due to grid disturbances.
Especially the power electronics of the converter of the wind turbine needs to be protected from any accumulation of humidity inside the converter and its power electronics.
It is known to heat the converter in critical situations (as described above) by using a fluid, which is part of a cooling system of the converter. The fluid might be water, circulated by a pump, and/or air, circulated by a fan.
The fluid is heated and circulated inside the converter for a pre-determined time period to ensure that no humidity is accumulated in the converter.
As soon as this time period is reached the power electronics of the converter can be activated and the wind turbine could be turned into operational mode next.
The pre-determined time period is known as “dry-out”-period of the converter.
The dry-out process as described above is started and controlled by installation instructions. It ensures that the converter is only started if the power electronics of the converter are dried out completely.
The duration of the respective dry-out period is chosen traditionally and based on experiences gathered in the past. Thus the duration is maximized to result in a guaranteed secure operation of the converter. Thus the chosen dry-out period results in a respective and non-optimized waiting time.
For example the dry-out period, which needs to be kept before a wind turbine is started for the first time or which needs to be kept if the wind turbine was disconnected from auxiliary power for one week, might be fixed with 24 hours, needed for heating and for the circulation of the fluid inside the converter.